1. Field of Invention
Various embodiments of the present invention relate to a microwave device and a manufacturing method thereof, and more particularly to a circulator puck using a magnetic material nano wire array and a manufacturing method thereof.
2. Description of Related Art
In microwave communication, a circulator is a device that that can be directly connected to an antenna. Connected to the antenna, the circulator plays the role of changing the connection state to and from transmission and reception. An isolator is a device that has a function of proceeding microwaves in only one direction just as a diode of in a semiconductor device.
FIG. 1 is a view for explaining operation principles of a circulator. As illustrated in FIG. 1, the circulator adjusts the direction of progress of a microwave using changes in the phase velocity of the microwave due to changes in the permeability of a magnetic material regarding the microwave. Such operations of the circulator are based on the principle of the magnetic material making precession motions as the magnetic moment is aligned (magnetization) when an external static magnetic field is applied.
In general, when a linear polarized microwave enters a magnetic material, the linear polarized microwave may be decomposed into two circular polarized microwaves. That is, the linear polarized microwave may be divided into a left-circular polarized light and a right-circular polarized light, and the permeability, that is the reaction of ferrite due to the magnetic field of each of the left-circular polarized light and the right-circular light will be different from each other. In other words, due to the difference of phase velocity between the permeability (μ′+) of the light polarized in the same direction as the precession and the permeability (μ′−) of the light polarized in the opposite direction, the direction of progress will rotate as illustrated in the enlarged part (p) of FIG. 1.
Therefore, in order to rotate the direction of progress of such a wave by a certain angle, the magnetic moment of the ferrite puck must be aligned in a certain direction, and in order to do this, a conventional circulator is manufactured to include a permanent magnet for applying a magnetic field.
Conventional circulators mostly have a waveguide structure illustrated in FIG. 2a or a microstrip structure illustrated in FIG. 2b. They may also be configured in other various structures such as a stripline structure or a lumped element structure. Waveguide type circulators include a waveguide 3, and microstrip structure circulators include a metal stripline 4.
Such a conventional circulator is fitted with a magnetic material ferrite puck and a permanent magnet. More particularly, a conventional circulator includes a ferrite puck 1 of a soft magnetic material and a permanent magnet 2 for applying a magnetic field to the ferrite puck.
The permanent magnet that accounts for a significant portion of a circulator increases the cost of the circulator, and further, it is difficult to integrate the circulator with a substrate.
Not only that, for a conventional circulator, an insulating ferrite puck has to be used to minimize the loss of microwaves, and such insulating characteristics of the ferrite cannot easily release the heat energy that is generated when high power microwaves are applied, causing nonlinear characteristics and consequently deteriorating the efficiency of the circulator.
The need to use a permanent magnet can be resolved by developing a puck that can operate even when an external magnetic field is not applied by using hard magnetic (permanent magnet) materials such as Sr (strontium) ferrite or Ba (barium) ferrite, but these materials have their unique magnetic characteristics and thus cause the problem of having to operate at high frequencies only. Therefore, there still remains the problem that such a circulator cannot be used in various frequencies, and also the problem of relatively high magnetic loss.